Water-distributing roller for lithographic plates



Dec. 28 ,"1926.

J. o. SANKER WATER DISTRIBUTING ROLLER FOR LIITHOG'RAPHIC PLATES Original ed Dec. 24,

' INVENTOR. M

Patented De c. 2831926.

UNITED STATES.

' uann PATENT OFFICE.

JOHN 0. SANKER, 0F NORWOOD, OHIO.

WATER-DISTRIBUTING ROLLER FOR LITHOGRAPHIC PLATES.

Continuation of application Serial No. 77,452, filed December 24, 1925. This application filed May 5, 1926.

Serial No. 106.953.

My invention relates to lithographic presses (having planographic plates) and particularly to improvements in rolls for distributing water for damping the printing plates of such presses.

][t is the object of my invention to provide metal distributing rolls for vthe damper rollers of lithographic presses, which are so constructed and treated that the tendency for the printing plates to become blurred will be avoided. v i

It is specifically the object of my invention to provide rolls for distributing films of aqueous acid solution on the damping rolls of lithographic presses which are preferably made ofsimilar material and material treated similarly to the etched planographic plates with which the lithographic printing is done, which prevent the blurring of the plates and consequently of printed sheets.

lln my application Serial #77A52 filed December 24th, 1925, of whichthis is a con tinuation, l have described the method of; manufacturing a distributing roller with which l have had marked success in lithographic work. Although the process of manufacturing the preferred type of distributing rollers is described in this application, further'study oil the principle involved in this invention has indicated that the results are adected by an electrical phenomtill background. ln addition to the treatment.

prior to the disposal of the plates on the printing roller, during the operation of the press, it is further necessary to spread a thin film 0t desensitizing or what is commonly called etching solution on the plates to keep them. from picking up ink from the form rollers.

For printing plates it has been found that.

a number oil dinerent materials may be used both for the material out which the plates are made, and for the solution for de-sensitia, ing or etching the plates. Consequently myinvention involves the use of dillerent mate rials with which the water distributing rollers may be made and diflerent chemical treatments of the distributing rollers prior to their insertion within the press mechanism depending on what material is used an electric couple, an electric circuit is established through the moisture on the damping rollers, and corrosion of the distributing roller occurs and the rusted portionsconsequently retain ink which is picked up from the damping rollers.

In the ensuing disclosure of my invention, it should therefore be noted that although I describe one modification otmy invention, other adaptations will readily occur to those skilled in the art without departing from the principle involved.

Referring to the drawings in which I have illustrated diagrammatically one standard type of offset'press,-

Figure 1 is' a perspective view of a fluid distributing roll.

Figure 2 is a diagrammatic sectional view of a press, which will illustrate clearly the till cooperating parts of a press with which my plates 2. With the rotation of the cylinder,

the printing plates 2 are carried into contact with the form rollers 3 from which the ink is picked up. The fo1'm ,rollers are supplied with ink from a series of intermediate rollers 4 which engage distributing riders 5 on which ink films are deposited by peripheral contact with a distributing drum 6. Ink is poured into the ink reservoir 7 into which a pivotally mounted roller 8 alternately dips and feeds as will be readily un derstood.

Prior to the application ot the ink to the wi l on which a thin film of some suit-able aqueous desensit-izing solution is peripherally distributed by a distributing roller 10. It is primarily in the provision of novel distributing rollers similar to that indicated at 10 that my invention is directed. The damping rollers are preferably of metal with cloth outer covers extending about the periphery of the rollers as indicated at 11. A ducker roller 12 also having an outer cloth coveris mounted on pivoted arms 13. The arms are connected with mechanism by which the ducker rollers are moved from peripherally engaging position with the distributing roller 10 to peripherally engaging position with the carrying roll 14 which revolves within the aqueous desensitizing solution pan 15.

For damping the printing plates, which in one form of mechanism with which my invent-ion has been particularly successful are made of aluminum, I prefer to use a desensitizing solution containing a weak phosphoric acid and gum arabic. H the printing plates are made of zinc or alloys of tin or zinc, I may use other acid or desensitizing solutions.

Up to the advent of my invention to the best of my knowledge and belief, lithographic presses have been equipped with brass distributing rollers. The brass rollers are not corroded by the desensitizing solution, but they have one serious defect. The damping rolls which pick up some ink during the peripheral contact with the printing plates, reconvey this ink to the distributing roll it it be of brass. The ink .is reconveyed fIOIIl the distributing roll to the ducker roll and eventually all the damping series of rolls and rollers become smeared with ink. As aresult the desensitizing soultidn is not fed in a smooth film and with continued operation the lack offeeding a continuous smoothfilm to the printing plates causes them to become blurred, and thus unsatisfactory lithographic printing is done.

The basis of my improvement in distributin g rollers is the provision of rollers made of such metallic constituency that the rollers will either be desensitized by the damping solution, or that they will be so treated that no electric couple with the printing plates, will be established which will result in a galvanic action which tends to'form rust spots on the distributing rollers. Under normal operating conditions, it will be preferable to make the distributing rollers of similar metal, and to treat the rollers in a similar manner as the printing plates, but it is within the scope of my invention to provide other means for using a distributing roller which will not form anelectric couple with the prir. ting plates.

Thus I provide means for preventing the ink working back to the ducker roller and so smearing up the whole system. I havev if the distributing roller be of aluminum,

the roller may be given a treatment with gum arabic and phosphoric acid, and a thorough drying, which will restore its original condition.

I have found that with aluminum plates, aluminum distributing rollers are most satisfactory; with zinc rollers are best; wit copper plates, copper rollers and the same principle may be followed through the entirerange of alloys of metals which are used for the manufacture of printing plates. -Further grooved or roughened distributing rollers may be used without departing from the principle of my invention, which is primarily related to the metal of which my distributing roller is ma e.

Although wooden rollers will avoid establi'shing an electric couple, the use of wooden rollers does not provide a satisfactory distributing system and I make no claim to distributing rollers which are not made of -metal or compounds of metal.

Having thus described my invention, what l claim as new and desire to protect by Letters Patent, is

- 1. In a lithographic press having metallic printing lat/es, a distributing roller for peripheral y distributing a film or aqueous desensitizing solution on damping rollers, said roller made of the same metal of which said plates are composed.

2. lln a lithographic press having metallic printing plates, a distributing roller for peripherally distributing a film of aqueous desensitizing solution on damping rollers, said roller made of the same metal of which said plates are composed, said roller prior to its use being subjected to a desensitizin treatment similar to that to which sai metallic printing plates have been subjected.

3. In combination with a lithographic' press having printing plates of I selected metallic constituency with portions of said plates etched and having unetched portions thereof desensitized to prevent the adhesion of ink thereto, means of continuously feeding into peripheral contact with said plates aqueous films of desensitizing solution, said means comprising a roller of similar selected metallic constituency as said plates.

plates, zinc distributing 7 4. In combination with a lithographic press having printing plates of selectedmetallic constituency with portions of said plates etched and having unetched portions thereof desensitized to prevent the adhesion of ink thereto, means of continuously feeding into peripheral contact with said plates aqueous films of desensitizing solution, said means comprising a roller of similar selected metallic constituency as said plates, and said roller prior to itsuse having been subjected to a similar desensitizing treatment as said plates.

5. In combination with a lithographic press having printing plates of selected metallic constituency with portions of said plates etched and having unetched portions thereof desensitized to prevent the adhesion of ink thereto, means of continuously feeding into peripheral contact with said plates aqueous films of desensitizing solution said means comprising a roller of selecte metallic constituency similarly treated as said plates.

6. In a lithographic press having metallic printing plates, a distributing roller for peripherally distributing a film of aqueous dampening solution on damping rollers, said roller made of similar metal of which said plates are composed.

7. In a printing press adapted to use planographic plates, a dampening mechanism for said plates, andlat least onemetal roller for distributing dampening solution on said plates, said roller composed of material inhibitive to the galvanic action of an electric couple between said roller and said plates.

8. In a printing press adapted to use planographic plates, a dampening mechanism for said plates, and at least one member for distributing dampening solution for said plates, said member composed of material other than Wood inhibitive to the galvanic action of an electric couple between said member and said plates.

J OHN. O. SANKER. 

